Answer:
C) Ca(OH)2
Note: The options from the question are wrong. The correct options are given below:
15. Exactly 3.705 kg of substance Y are needed to neutralise 100 moles of HCl(aq).
What could be substance Y?
A Ca B CaO C Ca(OH)2 D CaCO3
Explanation:
A) Ca + 2HCl ---> CaCl2 + H2
Molar mass of Ca = 40 g/mol
Mass of Ca required to neutralize 100 moles of HCl = 1/2 * 100 * 40 g = 2000g or 2 kg
B) CaO + 2HCl ---> CaCl2 + H20
Molar mass of CaO = 56.1 g/mol
Mass of CaO required to neutralize 100 moles of HCl = 1/2 * 100 * 56.1 g of CaO = 2805 g or 2.805 kg
C) Ca(OH)2 + 2HCl ---> CaCl2 + 2H2O
Molar mass of Ca(OH)2 = 74.1 g/mol
Mass of Ca(OH)2 required to neutralize 100 moles of HCl = 1/2 * 100 * 74.1 g = 3705 g or 3.705 kg
D) CaCO3 + 2HCl ---> CaCl2 + H2O + CO2
Molar mass of CaCO3 = 100 g/mol
Mass of CaCO3 required to neutralize 100 moles of HCl = 1/2 * 100 * 100 = 5000 g or 5.00 kg
Therefore, the correct option is C.
